The invention relates to a housing for a screw compressor and, more particularly, to a housing for a hermetic multi-rotor screw compressor.
Screw compressors typically have several different housing members. A housing must be provided for the rotor or rotors, and a separate housing is typically provided for the motor which drives the rotors. Separate housings are typically required due to the length of the rotors, and for other reasons.
These housing designs can be problematic in providing a hermetic compressor. Further, access to the rotor for servicing and the like is difficult in that entire housing members must be repositioned to access same, and these housings are heavy and bulky.
Multi-rotor screw compressors typically have multiple discharge ports, see for example U.S. Pat. No. 5,807,091 to Shaw. These discharge ports typically remove refrigerant or other compressed medium from the rotors in a radially outward direction and then convey this flow to a collection chamber for discharging a single stream. The positioning of these discharge ports and collection chambers impose a change in direction of flow on the refrigerant which can cause reduction in efficiency.
The motor portion of such compressors tends to general heat and requires cooling. Cooling cab be accomplished with oil or other cooling medium, and U.S. Pat. No. 6,045,344 shows a compressor wherein coolant is passed through the motor housing by an end suction which causes the cooling medium to pass through the entire motor assembly.
It is clear that the need remains for an improved housing for screw compressors so as to address the aforesaid disadvantages.
It is therefore the primary object of the present invention to provide such a housing.
It is a further object of the present invention to provide a housing including a discharge port which improves flow efficiency of refrigerant or other compressor medium.
It is a still further object of the present invention to provide such a housing which provides for simplified cooling of the motor.
It is another object of the present invention to provide a housing which has a low manufacturing cost.
Other objects and advantages of the present invention will appear hereinbelow.
The foregoing objects and advantages of the present invention have been readily attained.
In accordance with the present invention, a housing for a screw compressor is provided, which comprises a single-piece casting defining a motor housing section and a rotor housing section and having an inlet for compressor medium, an outlet end and a bridge member disposed between said motor housing section and said rotor housing section and defining an inlet side bearing housing; a discharge housing mounted to said outlet end and defining an outlet and a discharge side bearing housing; and at least one rotor disposed in said rotor housing section and rotatably mounted between said inlet side bearing housing and said discharge side bearing housing.
In accordance with one aspect of the invention, the inlet is arranged so as to introduce compressor medium into the housing between the motor housing section and the rotor housing section, by suction, which leads to cooling of the motor housing section as the compressor medium is passed to the rotors.
In accordance with a further aspect of the present invention, the bridge member extends inwardly from an inner surface of the housing so as to define an inlet side bearing housing for the rotors and motor, while allowing compressor medium to flow around the bridge through flow channels defined therebetween and to the rotors.
In accordance with yet another aspect of the present invention, the discharge housing defines discharge ports for the rotor which extend away from the rotor both radially and axially so as to provide for more efficient flow of compressor medium from the rotors to the discharge pipe.